(function(doc,win){
    var docEl=doc.documentElement,
        resizeEvt='orientationchange' in window ? 'orientationchange' : 'resize',
        recalc=function(){
            var clientWidth=docEl.clientWidth;
            if(!clientWidth) return;
            if(clientWidth>=750){
                docEl.style.fontSize='100px';
            }else{
                docEl.style.fontSize=100*(clientWidth/750)+'px';
            }
        };
    if(!doc.addEventListener) return;
    win.addEventListener(resizeEvt,recalc,false);
    doc.addEventListener('DOMContentLoaded',recalc,false);
})(document,window);